Files transfer between a remote home server and a local server

ABSTRACT

A method and system for providing a file utilizing information according to which the file is locally stored when the file is received from a remote server are disclosed. According to one embodiment, a method is provided which comprises receiving a request for the file, where the request comprises data identifying the remote server. The described embodiment further comprises checking that the file is locally stored, forwarding the file to the remote server when the file has been locally modified, and deleting the information according to which said file is locally stored.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to files transfer between a remote serverand a local server. Such a transfer is necessary when a user istemporarily connected to a local server different from a remote homeserver to which this user is usually connected.

2. Description of the Related Art

It is now very common that someone who travels needs to have access to aset of files, system files, data files or application files. So, thisperson can bring a portable computer with him, all the necessary filesbeing stored in this computer. It is often not very convenient to carrysuch an equipment. Moreover, nowadays, the files of a computer user areoften stored on a server, the home server. In this case, the user has totransfer all his files on the portable computer and he can forget someof these files. Thus, solutions have been developed to allow a user toaccess transparently to his own computer from another personal computer,generally by means of a local server.

A first method, TELNET, allows a user connected to a network with alocal computer to access a remote computer such that the local computeris a terminal of the remote computer. The term TELNET refers to a remoteconnection on the INTERNET that is made with the TELNET protocol. Whenusing electronic mail or FTP, a file transfer protocol, the localcomputer limits the interaction with the remote computer and the filemanagement between both computers is not very practical. It is alsopossible to open an interactive session with TELNET. Accordingly, oncethe connection has been established, the local computer is transparentand the user works as if he were directly attached to the remotecomputer. During the session, both computers are connected, what meansthat access times could be long, especially when the remote computer isoverburdened.

Another method is known as directory replication, a feature offered byservers equipped with MICROSOFT WINDOWS NT (registered trademark).Directory replication allows to set up and maintain identicaldirectories on multiple stations such as servers or personal computers.Updates made to the files or directories on one server are periodicallyreplicated to other stations in import directories. Replication is welladapted for read only files since import directories that receive copiesof the files are overwritten each time replication occurs. Anymodification made on a file in an import directory is lost at the nextreplication. Consequently, the user cannot be sure that themodifications he has made in an import directory will be saved; thesaving procedure has to be done manually, by means of specific commands.

SUMMARY OF THE INVENTION

It is therefore a general object of the present invention to provide fora method which allows to access a file in a remote computer from a localcomputer in an efficient way and to insure that any modification of thisfile is saved.

According to the invention, in a remote computer, a method for providinga file comprises the following steps:

receiving a request for this file,

identifying this file as being stored in a distant server,

requesting the distant server to send the file,

identifying this file as being used, and

forwarding this file.

Besides, in a local server, a method for transferring a file from a homeserver comprises the following steps:

receiving a request for this file, this request comprising the homeserver identification,

checking that this file is not locally stored,

requesting this file to the home server,

identifying the file as being locally used, and

forwarding said file.

A method for sending back the file to the home server, wherein is storedan information according to which said file is locally stored, comprisesthe following steps:

receiving a request for this file, the request comprising the homeserver identification,

checking that the file is locally stored,

forwarding the file to the home server when it has been locallymodified, and

deleting the information according to which this file is locally stored.

Advantageously, this method comprises a further step for sending aninformation to the home server when the file has not been locallymodified.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are described below by way ofexample only with reference to the accompanying drawings, wherein:

FIG. 1 represents the equipments involved in the invention,

FIG. 2 represents the main components of a local file server,

FIG. 3 represents the main components of a home file server,

FIG. 4 is a diagram showing the messages exchange between the client,the local server and the home server, and

FIG. 5 is a flow chart of the method used in the local server.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, a personal computer or client 10 is connectedto a local file server 11 by means of a local area network 12 itselfconnected to a wide area network 15, generally with a router 14. Inaddition, a remote home file server 17 is also connected to the widearea network 15 such as Internet either directly or through anotherrouter (not shown) and another local area network (not shown).

With reference to FIG. 2, the local file server 11 comprises a first LANadapter, 21 where LAN means “Local Area Network”. This adapter is usedto transmit and receive messages on the network with the client 10 andwith the home file server 17. Another component of the local file server11 is a first disk controller 22 such as a SCSI adapter (SCSI for “SmallComputer System interface”) or a RAID adapter (RAID for “Redundant Arrayof Inexpensive Disks”). The local server also comprises a firstprocessor 23 to perform the method which will be described further.

The local file server 11 comprises in addition a first memory 25 whichincludes two specific tables, the local client table LT1 and the guestclient table GT1. Each entry in these tables corresponds to a user andgives a pointer on one directory called the directory file.

With reference to FIG. 3, the remote home file server 17 is very similarto the local file server 11. It comprises a second LAN adapter 31, asecond disk controller 32, a second processor 23 and a second memory 35.This memory includes also a local client table LT2, a guest client tableGT2 and it further includes a remotely logged client table RT2.

With reference to FIG. 4, a file transfer between the home file server17-402 and the client 10-400 will now be described. There is a set ofmessages between the client and the local server 11-401 and another setof messages between the local server and the home server. There is nodirect exchange between the client 400 and the home server 402.

When the client or personal computer 400 is powered on, it first runsthe BIOS program 403 stored in a read only memory located in a LANadapter. The BIOS program performs a remote boot 406 on the local fileserver 401, using any usual protocol such as DHCP (“Dynamic HostConfiguration Protocol”) or BOOTP (“Bootstrap protocol”). The BIOSprogram sends a Connection request 404 to the local server 401 whichsends back a login application 405. The adapter of the personal computer400 uses a file transfer protocol such as TFTP (“Trivial File TransferProtocol”), FTP (“File Transfer Protocol”) or CIFS (“Common InvestmentFile System”) for downloading this login file from the local server 401.Subsequently, the personal computer 400 runs the login file whichprompts a user of this computer to enter a user identification andeventually a password 407. The local file server 401 checks whether theuser is one of its clients or not referring to the first local clienttable LT1 408. Assuming the user is not one of its clients and is aguest, this user should be stored in the guest client table GT1 if thisnot already done. The local server now requests the user to enter a homefile server identification 409-410. When this identification isreceived, the local server forwards 411 the client request to the homefile server 402. In response, the home server checks 412 that the useris one of its clients (referring to the second local client table LT2for instance) and acknowledges 413 the local server to accept this user.In addition, the home server informs the local server of the operatingsystem files needed for this user. Usually, most of these files areavailable at the local server and therefore need not to be transferredbetween both servers. Eventually, the home server sends a file includinguser specific data. The local server can transfer the operating files tothe client station 414 and the personal computer 400 can perform theloading of the operating system 415.

Additional information on Internet protocols can be found in a IBMCompany publication entitled: TCP/IP tutorial and technical overviewGG24-3376-05, October 1998, edited by the International TechnicalSupport Organization.

With reference to FIG. 5, a file transfer 50 is now described from thelocal server. First, a test 51 determines whether the client (user)using the client station is a guest or a local known client.

If the client is a local known user (“no” answer), the requested file issimply transmitted to the client 54.

If the client is a guest and requests a new file transfer, the localserver first checks 52 whether the file is in the local client directoryor not by means of the guest client table GT1.

If the file is in the local server (“yes” answer), the local serversends the file to the client 54.

If the file is not in the local server (“no” answer), the local serverrequests the file to the home server 53, stores this file in its memoryand its identification in the guest client table, and then forwards thefile to the client. The files modifications made by the client on thepersonal computer are saved in the local server, what is state of theart. Moreover, an indication that the file has been modified is storedin the guest client table. According to an optional feature, thisindication is also forwarded to the home server.

On the other hand, when this file is requested by the home server, thelocal server checks whether it has been modified or not.

If the file has not been modified (answer “no”), this information isforwarded to the home server.

If the file has been modified (answer “yes”), the modified file isforwarded to the home server. In any case, the file is deleted and theidentification of this file is removed from the guest client table GT1.

In the home file server 17, when a file has been requested by a firstlocal server, or when according to the above mentioned optional featurea file is modified in this local server, a corresponding information isstored in the remotely logged client table RT2 together with theidentification of the local server. Thus, when later this file isrequested again by the user from another server or from the home serveritself, the home server first checks if it appears in the remotelylogged client table RT2. If it is the case, this file is first requestedto the local server identified in the table RT2 and it is overwritten onthe version stored in the home server. The information according towhich the file is in the first local server is then deleted in theremotely logged client table RT2.

It then appears that the latest version of the file is always available,either in the home server or in a server identified in a table of thehome server.

The scope of the present invention is in no way limited to the aboveembodiments. In particular, any means or steps could be replaced byequivalent means, respectively steps.

1-2. (canceled)
 3. A method for providing a file, wherein is storedinformation according to which said file is locally stored when saidfile is received from a remote server, said method comprising thefollowing steps: receiving a request for said file, said requestcomprising said remote server identification, checking that said file islocally stored, forwarding said file to said remote server when saidfile has been locally modified, and deleting the information accordingto which said file is locally stored.
 4. The method according to claim 3further comprising a step for sending said information to said remoteserver when said file has not been locally modified. 5-8. (canceled)